Method and apparatus for policy-based content sharing in a peer to peer manner using a hardware based root of trust

ABSTRACT

Securely sharing content between a first system and a second system is provided. A hardware-based root of trust is established between the first system and a server. Content requested by a user and an encrypted license blob associated with the content is received by the first system from the server. A first agent on the first system connects with a second agent on the second system. The encrypted license blob and a sub-license request are sent from the first agent to a security processor on the first system. The first security processor decrypts the encrypted license blob, validates the sub-license request, and if allowed, creates a sub-license to allow the second system to play the content. The first security processor sends the sub-license to a security processor on the second system. The first system provides access to the content to the second system for future playback according to the sub-license.

FIELD

The present disclosure generally relates to the field of computingsystem architectures for securely processing digital content. Moreparticularly, an embodiment of the invention relates to sharing digitalcontent within a hardware-based root of trust.

BACKGROUND

On open computing platforms, such as a personal computer (PC) system forexample, when playing premium content (such as from a DVD, Blu-Ray,etc.), the digital rights management (DRM) processing and key managementare typically performed in software by a media player applicationprogram. These schemes are not well protected and there have beeninstances of hacking, resulting in pirated content and loss of revenueto content owners. When content is played, even though the mediadecompression (such as H.264, MPEG-2, etc.) is done in hardware, thecontent is in the clear in system memory and can be stolen withsoftware-based and/or hardware-based attacks. Due to these notedsecurity weaknesses, only lower fidelity (such as standard definition(SD)) content or less valuable high definition (HD) content is typicallydistributed to open computing platforms. Improvements to the securehandling of digital content by open computing platforms (such as a PC,for example) are desired.

In order for users to securely share content between open computingplatforms, in some current systems users are allowed to create domainsand add devices to a domain via cloud-based services. However, the usersmay want to be able to share content with friends and/or family in anad-hoc fashion without having to authorize the new devices for all oftheir content. In some cases, the user may want to allow one person ordevice to share a particular content title, and perhaps even justtemporarily. Existing services and systems do not provide suchcapabilities.

BRIEF DESCRIPTION OF THE DRAWINGS

The detailed description is provided with reference to the accompanyingfigures. The use of the same reference numbers in different figuresindicates similar or identical items.

FIG. 1 is a diagram of a secure content processing pipeline according toan embodiment of the present invention.

FIG. 2 is a diagram of a service provider server and security servicesinfrastructure according to an embodiment of the present invention.

FIG. 3 is a diagram of a client computing system according to anembodiment of the present invention.

FIG. 4 is a flow diagram of secure content processing according to anembodiment of the present invention.

FIG. 5 is a diagram of a secure content processing system according toan embodiment of the present invention.

FIG. 6 is a diagram of peer client computing systems according to anembodiment of the present invention.

FIGS. 7 and 8 are flow diagrams of content sharing processing accordingto an embodiment of the present invention.

DETAILED DESCRIPTION

Embodiments of the present invention comprise a system architecture thatprovides a hardware-based root of trust (HW ROT) solution for supportingdistribution and playback of premium digital content. In an embodiment.HW ROT for digital content and services is a solution where the basis oftrust for security purposes is rooted in hardware and firmwaremechanisms in a client computing system, rather than in software. Fromthis root of trust, the client computing system constructs an entiremedia processing pipeline that is protected for content authorizationand playback. In embodiments of the present invention, the security ofthe client computing system for content processing is not dependent onthe operating system (OS), basic input/output system (BIOS), mediaplayer application, or other host software. In order to compromise thesystem, one will need to compromise the hardware and/or firmwaremechanisms, as opposed to attacking the software running on top of theOS.

Embodiments of the present invention allow content providers toassociate a set of flexible content sharing policies with content thatis rented or purchased by a consumer. As long as the content sharingpolicies are followed and enforced by client computing systems, there isno need to contact cloud-based services to get permission for sharingcontent. There is no need for adding a client computing system to aspecified domain. Instead, the content license contains the sharingpolicies. Embodiments of the present invention provide for peer-to-peersub-licensing of content using a hardware-based root of trust forbinding the usage of the content to the receiving client computingsystem based on content provider policies. Embodiments of the presentinvention also enforce playback rights.

In the following description, numerous specific details are set forth inorder to provide a thorough understanding of various embodiments.However, various embodiments of the invention may be practiced withoutthe specific details. In other instances, well-known methods,procedures, components, and circuits have not been described in detailso as not to obscure the particular embodiments of the invention.Further, various aspects of embodiments of the invention may beperformed using various means, such as integrated semiconductor circuits(“hardware”), computer-readable instructions organized into one or moreprograms stored on a computer readable storage medium (“software”), orsome combination of hardware and software. For the purposes of thisdisclosure reference to “logic” shall mean hardware, software (includingfor example micro-code that controls the operations of a processor),firmware, or some combination thereof.

Embodiments of the present invention protect content protectionprocessing, key management processing, and content playback by usingfirmware and hardware in the CPU, chipset and integrated graphics/mediaengine of a client computing system 101 to perform these functions.Embodiments of the present invention provide end-to-end protection ofthe content as the content is processed by components within a computingsystem. FIG. 1 is a diagram of a secure content processing pipeline 100according to an embodiment of the present invention. Content 102 may beaccessible by a service provider (SP) server 104. Content 102 may be anydigital information, such as audio, video, or audio/video data, images,text, books, magazines, games, or application programs. Service providerserver 104 may include one or more servers for providing the content toa client computing system over any telecommunications channel (such asthe Internet, cellular networks, wired or wireless networks, etc.).Content may be protected by any known content protection technology 106(e.g., digital rights management (DRM) technology, cryptographictechniques, etc.) while stored in the SP server and during transfer tothe client computing system 101. In one embodiment, the content may beprotected by the Enhanced Privacy ID (EPID) signature verificationprotocol as discussed herein. In one embodiment, video data may beencrypted using the Advanced Encryption Standard (AES) cryptographicprocessing with CTR mode. The client computing system 101 may be a PC,laptop, netbook, tablet computer, handheld computer, smart phone,personal digital assistant (PDA), set top box, consumer electronicsequipment, or any other computing device capable of receiving, storingand rendering content.

Within the client computing system, content protection processing 110may be performed by a Security Processor 108. In one embodiment, thesecurity processor may be within a chipset of the client computingsystem. In an embodiment, the chipset comprises a platform control hub(PCH). In another embodiment, the Security Processor may be within theCPU of the client computing system. In another embodiment having asystem-on-chip (SOC) configuration, the Security Processor may beintegral with other system components on a single chip. In oneembodiment, the security processor comprises a Manageability Engine(ME). In other embodiments, other types of security processors may beused. The Security Processor is a subsystem implemented in hardware andfirmware that interacts with other components of the client computingsystem. The Security Processor operates by loading firmware code from aprotected flash memory region and executing the firmware code inprotected memory. Since the content protection processing is performedin hardware and firmware within the Security Processor, protection ofthe content may be improved over software-based systems.

Cryptographic key information may be sent from the security processorover a protected chip to chip interconnect 112 to a component containinga central processing unit (CPU) and an integrated graphics (GFX)/mediaengine. In an embodiment, the protected chip to chip interconnect 112comprises a secure Direct Media Interface (DMI) communications link tothe CPU/GFX component. DMI comprises a chip-to-chip interconnect withtwo unidirectional lanes of concurrent data traffic, and isochronoustransfer with improved quality of service. Data transferred over the DMIlink may be protected by known cryptographic processing techniques. Inan embodiment, the chip-to-chip secure link may be used for passingencrypted title keys over the DMI. Security is based on a shared secretbetween the PCH and the CPU. This shared secret may be established oneach power cycle and can vary between families of products, generationsand random groupings as needed to ensure protection and integrity of theshared secret. The DMI mechanism is independent of the OS, the BIOS, andsoftware running on the CPU. The DMI mechanism may be used to create atrust relationship between the security processor (in the PCH) and theCPU.

The GFX engine 114 may include content protection processing to decryptthe content. The GFX engine also includes decoder logic 121 toprocess/decode the decrypted audio/video content and pass theaudio/video content as media blocks to a graphics processing unit (GPU)within the GFX engine 114. The GPU includes security techniques,including using encoder logic 123, to protect the media blocks duringprocessing in memory. GFX engine 114 also includes composition logic 125to compose the image data to be shown on display 118. As the content isbeing handled within and between the security processor in the PCH andthe GFX engine in the CPU/GFX component, the content may be protected bya hardware protected data path 116. In an embodiment, the hardwareprotected data path comprises a Protected Audio Video Path (PAVP) tomaintain the security of the content. PAVP also supports an encryptedconnection state between system components. By using the PAVP, thesystem may further protect the content during transfer between systemcomponents and within memory.

The interface between the GFX engine, the PCH, and the display 118 maybe implemented by protected wired/wireless display links 120. In oneembodiment, display data sent from the GFX engine via a memory throughthe PCH to the display may be protected by a High-Bandwidth DigitalContent Protection (HDCP) content protection scheme. The HDCPspecification provides a robust, cost-effective and transparent methodfor transmitting and receiving digital entertainment content tocompliant digital displays. In an embodiment, the wired link may beimplemented according to the HDCP Specification, Revision 2.0, availablefrom Digital Content Protection, LLC, or subsequent revisions. HDCP maybe employed to deter copying of the display data as the data travelsover a DisplayPort, Digital Visual Interface (DVI), High-DefinitionMultimedia Interface (HDMI), Gigabit Video Interface (GVIF), or aUnified Display Interface (UDI) connection. The HDCP revision 2.0specification addresses emerging usage models that let end usersconveniently connect displays, devices and home theater systems viastandard protocols and interfaces like TCP/IP, USB, Wi-Fi andWirelessHD. The HDCP revision 2.0 specification uses standards-based RSApublic key and Advanced Encryption Standard (AES) 128-bit encryption forrobust content protection. In an HDCP system, two or more HDCP devicesare interconnected through an HDCP-protected interface. The audiovisualcontent protected by HDCP flows from the Upstream Content ControlFunction into the HDCP system at the most upstream HDCP Transmitter.From there, the HDCP content, encrypted by the HDCP system, flowsthrough a tree-shaped topology of HDCP receivers over HDCP-protectedinterfaces.

The HDCP content protection mechanism includes three elements: 1)Authentication of HDCP receivers to their immediate upstream connection(to an HDCP transmitter). The authentication protocol is the mechanismthrough which the HDCP transmitter verifies that a given HDCP Receiveris licensed to receive HDCP. 2) Revocation of HDCP receivers that aredetermined by the DCP to be invalid. 3) HDCP encryption of audiovisualcontent over the HDCP-protected interfaces between HDCP transmitters andtheir downstream HDCP receivers. HDCP receivers may render the HDCPcontent in audio and visual form for human consumption. HDCP receiversmay be HDCP repeaters that serve as downstream HDCP transmittersemitting the HDCP content further downstream to one or more additionalHDCP receivers. In one embodiment, display data sent to the display 118may be sent over a protected wireless display (WiDi) link 127 using802.11n wireless local area network (WLAN) technology.

As can be seen from FIG. 1, in embodiments of the present invention,from the time the content is received from the service provider server104 until the content is displayed on the display 118, no cryptographickey or content is available in unencrypted form to any software orunauthorized hardware running on the computing system. Further, memoryprotection for video data is offered over the whole chain across thedecrypt, decode/encode, compose and display pipelines. This capabilityis offered at the full memory bandwidth without compromising overallsystem performance.

FIG. 2 is a diagram of a service provider server 104 and a securityservices component 202 according to an embodiment of the presentinvention. In an embodiment, security services component 202 maycomprise one or more servers and/or components. In an embodiment, thesecurity services component may be operated by the manufacturer of oneor more components of the client computing system. The security servicescomponent provides capabilities for controlling client computing systemsin the field. The security services component comprises a manufacturingcomponent and a deployment component. The manufacturing componentincludes a certificate issuance component 218, a key generation (KeyGen) component 220, and a fuse programming (Fuse Prog) component 222.Certificate issuance 218 generates and issues public key certificates toeach of the client computing platforms. Key Gen 220 is responsible forgenerating the private and public key pairs as needed for embedding intothe client computing platforms. Fuse programming 222 is responsible forprogramming the fuses on the manufacturing floor with appropriate valuesin a robust and secure manner. These values would be used by the clientcomputing platform to build up the trust anchors and key ladders insidethe security processor.

The deployment component includes a certificate issuance component 204,a key generation (Key Gen) component 206, and a revocation manager 208.Certificate (Cert) issuance component 204 issues a digital certificatefor the SP Server and Client components giving them the authorization tointeract with such client systems for service deployment. Key generation(Key Gen) component 206 generates a cryptographic signing key pair, aroot key pair, digital certificates, and group public keys, and signsthe group public keys for each group. Revocation manager 208 determinesidentifiers and signatures of client computing systems to be added to arevocation list (RL), updates the RL, and distributes updated RLs.

The SP server 104 communicates over network 201 (such as the Internet)with the client computing system. The service provider server comprisesa SP server application 212 and a SP server agent 210. The SP serverapplication provides content browsing capabilities. The SP server agent210 controls the sending of client specific messages, managescryptographic keys and authorized user tokens, and maintains contentdelivery service status (for deployment purposes 212 and 210 could bephysically different servers firewalled and separated). Contentencrypter 214 accepts content 102 and encrypts the content for securedelivery to a client computing system. Content server 216 sends theencrypted content to the client. Key server 226 is responsible forprovisioning the title keys to the client computing systems within anauthenticated session. Server certificate 224 is used by the SP serveragent to participate in mutual authentication and establishment of theauthenticated session with the client computing systems. Communicationslinks between SP server agent 210, key server 226, and content server216 are protected by well accepted information security practices. Thekey server has the highest network and access protection to ensure onlyauthorized parties are able to reach it and the keys managed by the keyserver are isolated and firewalled from attackers from outside networkentities. The SP server agent or the key server has access to theprivate key associated with the server certificate 224. In anembodiment, this private key and all operations done with this privatekey are protected using a hardware security module (HSM) (not shown inFIG. 2) on the server.

In an embodiment, the cryptographic scheme used to authenticate theclient computing system with the SP server comprises a cryptographicauthentication protocol protecting a user's privacy based on the use ofzero-knowledge proofs. In an embodiment, the cryptographicauthentication protocol comprises the Enhanced Privacy ID (EPID) scheme,a Direct Anonymous Attestation (DAA) scheme with enhanced revocationcapabilities. EPID mitigates the privacy issues of common Rivest,Shamir, Adleman (RSA)—public key infrastructure (PKI) securityimplementations where every individual is uniquely identified for eachtransaction. Instead, EPID provides the capability of remote attestationbut only identifies the client computing system as having a component(such as a chipset) from a particular technology generation. EPID is agroup signature scheme, where one group's public key corresponds tomultiple private keys, and private keys generate a group signature whichis verified by the group public key. EPID provides the security propertyof being anonymous and unlinkable—given two signatures, one cannotdetermine whether the signatures are generated from one or two privatekeys. EPID also provides the security property of beingunforgeable—without a private key, one cannot create a valid signature.

Generally, setting up a secure communications channel with EPID may beaccomplished as follows. A first party (such as the client computingsystem) sends an EPID certificate to a second party (such as the serviceprovider server). Never knowing the identity of the first party and onlyknowing the first party is a computing platform with a trusted securityprocessor, the second party authenticates the first party. The firstparty then authenticates the second party using the second party'spublic key certificate. Since the second party doesn't require privacy,the second party's public key certificate may not be an EPID certificate(but it could be). The parties may then enter into a Diffie-Hellman (DH)key exchange agreement.

Various suitable embodiments of DAA and EPID are described in thefollowing co-patent applications, incorporated herein by reference: “AnApparatus and Method of Direct Anonymous Attestation from BilinearMaps.” by Ernest F. Brickell and Jingtao Li, Ser. No. 11/778,804, filedJul. 7, 2007; “An Apparatus and Method for a Direct AnonymousAttestation Scheme from Short-Group Signatures,” by Ernest F. Brickelland Jingtao Li, Ser. No. 12/208,989, filed Sep. 11, 2008; and “DirectAnonymous Attestation Scheme with Outsourcing Capability,” by Ernest F.Brickell and Jingtao Li, Ser. No. 12/286,303, filed Sep. 29, 2008. Inother embodiments, other authentication and attestation schemes may alsobe used.

The client computing system comprises at least three maincomponents—host software, chipset hardware/firmware, and theCPU/GFX/Media engines. It is assumed in embodiments of the presentinvention that the host software is untrusted. Even if the host softwaregets attacked, no secrets will be compromised. Host software isresponsible for network connection to SP server 104 and downloadingmedia from content server 216. Host software acts as a proxy betweenvarious SP servers and the chipset hardware/firmware. Host softwaresends encrypted content directly to the graphics hardware after thechipset hardware/firmware has completed title key unwrap and injectioninto the CPU/GFX component.

Chipset hardware/firmware is responsible for all protected processing,taking the role of the protected device for content protectionprocessing. In an embodiment, the chipset hardware/firmware sendsprotected title keys to the graphics hardware using the DMI mechanism.

The CPU/GFX component is responsible for final stream decryption, decodeand display. The GFX engine is a passive device, making no policydecisions. When asked, the GFX engine simply decrypts the content, thendecodes the submitted video slices. In an embodiment, the GFX engine(with protected media encoders) re-encrypts the display content for HDCPoutput protection over HDMI and wireless (e.g. WiDi) displays.

A protected client computing system must be remotely identified by aservice provider before sending highly sensitive information. Themechanism used to identify the platform must not violate user privacy.Embodiments of the present invention provide a protected mechanism for aservice provider to verify over the network that the service providerserver is communicating to a suitable client computing system andtransfer title keys and other confidential material to that clientcomputing system. In one embodiment, the protocol utilized to establisha protected session between the service provider server and the clientcomputing system is EPID. EPID allows for a single public key toanonymously verify the signature generated by N-private keys in what iscalled an EPID group. To implement EPID, each chipset contains a uniqueprivate key blown into the platform control hub (PCH) fuses duringsilicon manufacturing. In an embodiment, the chipset manufacturer places1,000,000 private keys in a single group and produces 400 groups foreach chipset produced. In order to act as the EPID verifier, eachservice provider will be provisioned with these 400 public keys.

Once a protected EPID session has been established, the service providerserver is free to exchange protected confidential information with theprotected client computing system. For content streaming, protectedtitle keys may be passed from an SP server to the security processor inthe chipset. The security processor sends the protected title keys tothe graphics and audio hardware. At this point, encrypted video andaudio content can be directly sent from a content server 216 to clientcomputing system graphics and audio hardware which decrypts, decodes,and displays the content. For downloading content, the securityprocessor binds the title keys to the client computing system using aunique platform storage key (again burned into PCH fuses duringmanufacturing) and returns the bound keys to media player software. Whenplayback is desired, the bound title keys are re-submitted to thesecurity processor, which unbinds and sends them in a protected mannerto the graphics and audio hardware.

FIG. 3 is a diagram of a client computing system 101 according to anembodiment of the present invention. A service provider (SP)player/media browser software application 302 may be included in thesoftware stack to interface with the SP server 104 over a network 201such as the Internet. The SP player/media browser 302 allows a user tobrowse content offerings of the service provider and to select contentto be delivered from the SP server to the client computing system. TheSP player/media browser provides user interface controls for the user tomanage a content library and to control the selection, downloading, andplayback of content. The SP player/media browser interacts with serviceagent 304. Service agent 304 comprises a software application providedby a service provider that is authorized to access the features of theclient computing system supporting end-to-end content protectionaccording to embodiments of the present invention. The service agentinterfaces with various SP player/media browser application programminginterfaces (APIs) (not shown in FIG. 2). Service agent 304 comprises amedia player component 306. The media player provides the content playerfunctionality (e.g., controlling playback).

SP client application 308 enables the SP player/media browser 302 andthe service agent 304 to access content protection features on theclient computing system's hardware and firmware and for relayingmessages to the service provider server 104. In an embodiment, the SPclient application comprises a host agent software development kit (SDK)including content protection APIs. In an embodiment, the SP clientapplication communicates with the security processor 314 in the platformcontrol hub (PCH) 312 of the chipset.

Audio driver 311 provides an interface between the media player andaudio decrypt hardware 316. Similarly, graphics (GFX) driver 310provides an interface between the media player and the GFX engine 320.In an embodiment, the PCH 312 comprises security processor 314, whichexecutes firmware to provide content protection functionality, alongwith other well known system functions. In an embodiment, the securityprocessor may be implemented by a Manageability Engine (ME). As contentis handled by the PCH 312 and the GFX engine 320, the content may beprotected at least in part by Protected Audio Video Path (PAVP)components 318, 322 in the PCH hardware/firmware and GFX enginehardware, respectively.

FIG. 4 is a flow diagram of secure content processing according to anembodiment of the present invention. At block 402, a user of the clientcomputing system uses SP player/media browser 302 to browse, discover,and purchase content from one or more service providers. At block 404,mutual authentication of the SP Server 104 and the client computingplatform 101 is performed. An authenticated session is established. Keyblobs with usage rights for a given set of content are provisioned. Thekey blobs are bound to the client computing system to ensure that thesystem is both confidentiality and integrity protected as necessary.

The client computing system then gets the encrypted content at block 406from content server 216 over network 201 (for streaming operations) orfrom local storage on the client computing system (for contentpreviously purchased, downloaded, and stored). The system is prepared towork on video slices (e.g., sub-frame). As a result, the hardware canprocess the data as soon as the first slice of data is submitted.

At block 408, the user initiates playback of the selected content usingthe SP player/media browser 302. The key blob is submitted to thesecurity processor 314 for unpacking and extracting of the title key.When that is done, the title key is loaded by the security processorinto the graphics hardware 320 for decryption. The SP player/mediabrowser submits the encrypted content to the media processing enginewithin GFX engine 320 at block 410. The GFX engine decrypts the contentusing the title keys and re-encrypts the content using a local protectedkey. Re-encrypted data may be stored in protected local or systemmemory. The re-encrypted content is subsequently obtained, decrypted,and decompressed at block 414. The decrypt is performed first. Once thedata is decrypted, the data is decoded/decompressed. Once the data isdecompressed, the data is re-encrypted and passed to the compositionengine via the system memory. Once the composition is finished, the datais again protected and passed using system memory to the display engine.In an embodiment, each component along the way has the ability todecrypt, process and re-encrypt as necessary.

At block 416, the GFX engine re-encrypts the media content using HDCPtechnology (in an embodiment) and delivers the content to the displayfor viewing by the user. At each step of the process, the content isnever in the clear where it is accessible by software or unauthorizedhardware components running on the client computing system.

FIG. 5 is a diagram of a secure content processing system according toan embodiment of the present invention. A SP server 104 interacts overnetwork 201 to client computing system 101. Client computing systemcomprises first 500 and second components 502. In an embodiment, thefirst component comprises a CPU and GFX component, and the secondcomponent comprises a platform control hub (PCH). In another embodiment,the first and second components may be combined into a single componentin a system-on-a-chip (SOC) implementation. First component 500 includesa plurality of processor cores 504, and GFX engine 320. Processor cores504 execute various components of host software (SW) 506 (as describedin FIG. 3), a client certificate 508, fuses 521, and a shared secret519. Host SW reads data, including encrypted content previously obtainedfrom a SP server or tangible media (such as a DVD, Blu-Ray, or otherstorage technology), from hard disk drive (HDD)/solid state drive (SSD)510. In an embodiment, Host SW comprises at least a SP player/mediabrowser application 302, a service agent 304, and a SP clientapplication 308. In an embodiment, HDD/SSD includes one or more userprofiles 511.

GFX engine 320 comprises a plurality of components. Mediaencrypt/decrypt engine 520 comprises logic to encrypt and decryptcontent. Media encode/decode engine 522 comprises logic to encode anddecode content. GFX Composition (Comp) engine 524 comprises logic toconstruct display images. Display engine 526 comprises logic to pass thecomposed display images to the display. Display encrypt/decrypt engine528 comprises logic to encrypt and decrypt display data prior to sendingthe display data to display 538 over protected link 527. Memoryencrypt/decrypt engine 530 comprises logic to encrypt and decrypt datastored in protected intermediate surfaces 534 in memory 536. Memory 536also includes logic to implement confidentiality and integrity protectedmemory operations 532.

Second component 502 comprises a plurality of components, some of whichare not shown in order to simplify FIG. 5. Second component comprises asecurity processor 314. Security processor includes firmware and/orhardware logic to provide attestation, provisioning key management,output control, and ad matching operations 516 for the client computingsystem. Security processor also includes fuses 517, shared secret 519,and trust anchors 518 for supporting a PKI such as verification keys andkey hierarchy information. Fuses 521, 517 are programmed into thehardware of the first and second components during manufacturing of thechipset with key material for EPID use. The hardware root of trust isbuilt up from the information programmed into the fuses on themanufacturing floor when the client computing system is manufactured.This ensures that each individual client computing system is unique, yetprivacy protected. Shared secret 519 is hard-coded into the hardware ofthe first and second components during manufacturing of the chipset andCPU/GFX components. In an embodiment, the shared secret may be used insetting up the secure chip to chip communications channel over the DMIlink 538.

Client computing system also includes a protected real time clock 513for providing secure clock services, a display 538, and a non-volatilememory (NVM) 512. In an embodiment, the protected real-time clock may beseeded by a third party, and may be virtualized for multiple serviceproviders. The NVM may be used to store the firmware image for thesecond component, as well as to store temporary data (such as integrityand state information) for security processor processing operations.

In an embodiment, a processing flow may be described as follows. SPplayer/media browser 302 presents a user interface to the user. The usergoes to the service provider's web site to browse available content. TheSP web site has an auto detection capability to determine if the user'sclient computing system has integrated within it the capability ofauthenticating with the SP server 104. If capable, the user is allowedto choose content. The content may be bought, rented, or subscribed to,or may be streamed. The user pays for the content. SP player/mediabrowser 302 invokes security processor 316 to authenticate the clientcomputing system 101 with the SP server 104. In an embodiment, theauthentication uses EPID technology. The client computing system 101 isauthenticated at least in part by having the SP server 104 verify theclient computing system's certificate 508, perform a revocation check,and verify a certification path to a certificate authority (using theEPID protocol in one embodiment). When both the client computing system101 and the SP server 104 are authenticated, a secure communicationschannel may be set up based on the EPID protocol in one embodiment. Inan embodiment, once the secure communication channel is set up, acommand set may be used for end to end content protection capabilities.

The SP Server 104 provisions an encrypted title key to the clientcomputing system, with constraints on usage of the content (e.g., time).The SP server sends the encrypted title key over the secure channel tosecurity processor 314. Security processor 314 decrypts the encryptedtitle key, using its own key hierarchy. Security processor 314 uses astorage key to re-encrypt the newly decrypted title key to form a keyblob. The key blob is bound to the client computing system for aspecified time period. Security processor 314 sends the key blob to SPplayer/media browser 302 running in the CPU core. SP player/mediabrowser 302 stores the key blob in HDD/SSD 510. SP player/media browser302 then downloads the user-selected encrypted content. In oneembodiment, the downloaded encrypted content may be stored in a contentcache 552 in the HDD/SSD 510.

When a user wants to play the content, the SP player/media browser 302submits the key blob back to the security processor 314. The securityprocessor verifies the signature of the key blob, and checks usageconstraints such as time, for example. The security processor 314 sendsthe encrypted title key over the encrypted channel (e.g. DMI link 538)to the media encrypt/decrypt component 520 of the GFX engine 320. Thesecurity processor instructs the SP player/media browser that theGFX/media engine is ready to process the encrypted content. In anembodiment, the SP player/media browser 302 reads the encrypted contentfrom content cache 552 in HDD/SDD 510, or obtains the encrypted contentfrom the SP server 104 over the network 201 (for a streamingapplication), and sends the encrypted content to the GFX engine slice byslice.

The GFX engine 320 processes the encrypted content in a slice by slicemanner. For each slice, the SP player/media browser reads the sliceheaders in the clear. The rest of the slice is encrypted so that the SPplayer/media browser cannot access the content. The SP player/mediabrowser keeps track of playback state information using aninitialization vector. The media encrypt/decrypt engine 520 decrypts thecontent using the title key, after decrypting the encrypted title keyreceived from the security processor. In one embodiment, the output dataof the media encrypt/decrypt engine is still compressed according to thewell-known H.264 encoding scheme. In other embodiments, other encodingschemes may be used. The media encode/decode engine 522 decodes eachslice and then re-encrypts the slice using memory encrypt/decrypt 530.The re-encrypted content slice is stored in protected intermediatesurfaces 534 in memory 536. GFX composition engine 524 controls thecomposition of the image to be displayed on the display, including theforeground and background images, windows, etc. The GFX compositionengine obtains the re-encrypted content slices from protectedintermediate surfaces 534 in memory 536 to generate the composed image.The GFX composition engine 524 sends the composed image data to thedisplay engine 526.

The display engine uses display encrypt/decrypt engine 528 to decryptthe composed image from the encryption that was used to store thecontent slices in memory 536. The display engine 526 uses the displayencrypt/decrypt engine to re-encrypt the composed image data accordingto the HDCP technology, in one embodiment. The encrypted composed imagedata is sent by the GFX engine 320 over the protected chip to chip datainterface (e.g., DMI link) 538 to the second component 502, for transferto the display 538 over protected display interface link 527.

In an embodiment, there can be any number of concurrent, independentcontent streams being processed by the client computing system. Eachcontent stream has its own cryptographic context so as not to interferewith other streams. This also allows for the client computing system toensure that any kind of attack or compromise on one stream does notaffect the other content streams.

In an embodiment, HDD/SDD 510 comprises at least one user profile 511and an ad cache 550, both of which are discussed further below. In anembodiment, client computing system comprises one or more sensors 554coupled to second component 502. Sensors sense the environmentsurrounding the client computing system and report sensor information tosecurity processor 314 for use by attestation, provisioning keymanagement, output control, and dynamic context based ad matchingcomponent 516. In an embodiment, sensors may include a GPS system,accelerometer, compass, vibration detector, and/or other sensors.

Embodiments of the present invention use the security capabilitiesdescribed above to support secure sharing of content in a peer to peermanner and interpreting of policies associated with shared content viasub-licensing.

FIG. 6 is a diagram of peer client computing systems according to anembodiment of the present invention. Client computing system A 602 andclient computing system B 604 may be configured as described in FIG. 5for client computing system 101. Client computing system A 602 maycommunicate with Service Provider (SP) Server 104 over network 201 toobtain content 608 for playback on client computing system A. Clientcomputing system A 602 may also communicate with client computing systemB 604 over local network 606. Local network 606 may comprise any meansof communication between devices, such as wireless (e.g., WiFi), wired,Bluetooth, near field communications (NFC), infrared (IR), and so on.Local network 606 may also be coupled to network 201. In an embodiment,network 201 and local network 606 may be the same network. In anembodiment, when client computing system A obtains content 608, clientcomputing system A also obtains license blob 610 that accompanies thecontent. The license blob may specify usage policies of the content byclient computing system A and/or other devices. The license blob may beencrypted by SP server 104 prior to delivery of the license blob toclient computing system A to deter tampering. The license blob may bedecrypted and read by the security processor 618 within the clientcomputing system A.

Client computing system A comprises sharing agent A 614. A sharing agentmay be a component that securely interacts in a peer to peer manner withone or more sharing agents on other client computing systems. In anembodiment, a sharing agent may be a standalone software program, or maybe integrated into an application program running on a client computingsystem (such as SP player/media browser 302, for example). In anembodiment, a sharing agent may be embodied in host software 506. Clientcomputing system B 604 comprises sharing agent B 616. In an embodiment,sharing agents A and B communicate using a content sharing protocol.Client computing system A comprises security processor A 618, and clientcomputing system B comprises security processor B 620. As discussedabove, a security processor may be implemented in firmware, hardware, ora combination of firmware and hardware. Security processor A andsecurity processor B interact to create a logical private and secureconnection between each other. In an embodiment, this connection may beused to securely transfer sub-license 612 from security processor A tosecurity processor B. The logical connection may be over network 201,local network 606, or peer-to-peer directly between client computingsystems using the sharing agents.

Security processor A 618 creates sub-license 612 based at least in parton license blob 610 for content 608, and may send the sub-license toother devices. The sub-license defines the policies of acceptable usageof content 608 by client computing system B 604 (the peer devicereceiving the sub-license and the content). In other words, thesub-license comprises policies defining restrictions on sharing thecontent between client computing systems.

In embodiments of the present invention, the license blob received fromthe SP server 104 may specify sub-license policies. For example,sub-license policies may comprise any one or more of the following:

Give-Max-Count—The number of permanent copies to other devices.

Loan-Max-Count—The number of loans.

Loan-Max-Duration—The length of time the loan is valid.

View-Max-Duration—The length of time that the content (such as a movie)can be viewed after first play.

Loan-Max-Hops—The number of times sub-licensed content (such as a movie)can be loaned.

Max-Play-Count—The number of times a loaned content (such as a movie)can be played.

Active-After-Loan—Will the content remain active on the lender deviceafter it is loaned to another device?

Active-After-Give—Will the content remain active on the giver's deviceafter it is given to another device?

Give-Max-Quality—The maximum quality of the content when it is given toanother device (e.g. resolution or frames per second).

Loan-Max-Quality—The maximum quality of the content when it is loaned toanother device (e.g. resolution or frames per second).

Other sub-license policies may also be defined.

FIGS. 7 and 8 are flow diagrams of content sharing processing accordingto an embodiment of the present invention. At block 702 of FIG. 7, auser may order content for a client computing system A. In anembodiment, the content may be purchased. In another embodiment, thecontent may be obtained without charge, but with certain license rightsattached to the content. In another embodiment, the content may beobtained via a loan, with certain license rights attached to thecontent. In an embodiment, the user obtains the content via digitaldownload from another computing device using the SP player/media browsercomponent 302. In an embodiment, the content may be obtained from SPserver 104. In other embodiments, other distribution mechanisms may beused.

In an embodiment, the SP player/media browser may be directed to a moviestorefront web site, for example, and the user purchases a movie usingwell known user interface techniques. In an example, the contentprovider may allow the user to loan (i.e., sub-license) the content fivetimes with selectable policies, one of which may provide for a permanentloan to another device, but the remaining four sub-licenses may be setto expire within at most 24 hours from the first playing of the content,and the loaned content may played back starting within at most one weekfrom delivery. In various scenarios, the content provider (e.g., licenseholder) can further restrict these values and policies. The contentprovider may define that the loaned copies of the content cannot befurther loaned by the lender (i.e., a Loan-Hop-Count may be zero). Manyscenarios of usages and transfers may be defined by the license andsub-licenses of embodiments of the present invention.

At block 704, SP server 104 encodes sub-license information into a datastructure called a license blob. For example, the sub-licensinginformation for content that is a movie denoted M1 might include anOriginator-ID, Give-Max-Count=1, Loan-Max-Count=4, Loan-Max-Duration=1week, View-Max-Duration=24 hours, Loan-Max-Hops=0, and so on. Thesub-licensing information may also include other information requiredfor content playback such as decryption keys, first-license policies,etc. In an embodiment, the license blob may be encrypted.

At block 706, in one embodiment. SP server 104 securely transmits therequested content and the associated license blob to the clientcomputing system A 602. Client computing system A may then use thecontent based at least in part on the license policies defined in thelicense 610, which may be extracted from the received license blob. Atsome point in time, the user of the content may want to share thecontent with another device. For example, the user may decide to give acopy of the content to someone who has another device. At block 708,sharing agent A 614 on client computing system A connects to sharingagent B 616 on client computing system B 604 to share the sub-licensefor the content (which is contained in the encrypted license blob 610).At block 710, sharing agent A sends the license blob to securityprocessor A 618 with a sub-license request. At block 712, sharing agentA 614 and sharing agent B 616 create a secure communications sessionbetween security processor A 618 and security processor B 620 tofacilitate transfer of the license blob from client computing system Ato client computing system B. In an embodiment, creating the securecommunication session uses EPID. Processing continues on FIG. 8.

At block 802 of FIG. 8, security processor A decrypts the receivedlicense blob 610, extracts playback information, validates thesub-license request and, if allowed, creates a sub-license 612 to allowclient computing system B to play the content. In an embodiment, thesub-license may define that client computing system B has ownership ofthe content, but no transfer rights. At block 804, security processor Asends the sub-license 612 to security processor B, using the securecommunications session, sharing agent A and sharing agent B. If thesub-license transfer is successful, at block 806, security processor Amodifies the license blob 610 to reflect the current sharingtransaction, re-encrypts the license blob, and returns the license blobto sharing agent A. At block 808, security processor B encrypts thesub-license with its own unique key and sends the encrypted sub-licenseto sharing agent B. At block 810, sharing agent B stores the sub-licensein a memory of client computing system B.

At block 812, client computing system A provides access to the contentto client computing system B. In an embodiment, this may be accomplishedusing sharing agent A and sharing agent B to communicate directly toeach other to send a complete copy of the content from client computingsystem A to client computing system B. In another embodiment, thecontent may be streamed in portions from client computing system A toclient computing system B, contained in a shared file mutuallyaccessible by the client computing systems, progressively downloaded(which allows for starting playback as soon as possible), or stored on anetwork file server. Furthermore, client computing system A mayre-encode or re-encrypt the content to suit the capabilities or trustlevel of client computing system B, or if sub-licensing policies requirere-encoding/re-encryption.

At block 814, client computing system B may commence playback of thecontent according to the rights specified in the sub-license.

Reference in the specification to “one embodiment” or “an embodiment”means that a particular feature, structure, or characteristic describedin connection with the embodiment may be included in at least animplementation. The appearances of the phrase “in one embodiment” invarious places in the specification may or may not be all referring tothe same embodiment.

Also, in the description and claims, the terms “coupled” and“connected,” along with their derivatives, may be used. In someembodiments of the invention, “connected” may be used to indicate thattwo or more elements are in direct physical or electrical contact witheach other. “Coupled” may mean that two or more elements are in directphysical or electrical contact. However, “coupled” may also mean thattwo or more elements may not be in direct contact with each other, butmay still cooperate or interact with each other.

Thus, although embodiments of the invention have been described inlanguage specific to structural features and/or methodological acts, itis to be understood that claimed subject matter may not be limited tothe specific features or acts described. Rather, the specific featuresand acts are disclosed as sample forms of implementing the claimedsubject matter.

The invention claimed is:
 1. A machine implemented method for operatinga first client computing system to securely share content between thefirst client computing system and a second client computing system,comprising: receiving, by the first client computing system, from aservice provider server, content requested by a user and an encryptedlicense blob associated with the content, the first client computingsystem having a first general purpose hardware processor and a firsthardware security processor that includes first unique and privacyprotected information of a first manufacturer of the first clientcomputing system; connecting, by the first client computing system, afirst sharing agent operated by the first general purpose hardwareprocessor with a second sharing agent operated by a second generalpurpose hardware processor on the second client computing system, thesecond client computing system, in addition to the second generalpurpose hardware processor, further including a second hardware securityprocessor that includes second unique and privacy protected informationof a second manufacturer of the second client computing system; sending,by the first client computer system, the encrypted license blob and asub-license request from the first sharing agent operated by the firstgeneral purpose hardware processor to the first hardware securityprocessor on the first client computing system; creating, by the firstsharing agent of the first client computing system in cooperation withthe second sharing agent of the second client computing system, a securesession between the first hardware security processor of the firstclient computing system and the second hardware security processor ofthe second client computing system, wherein the unique and privacyprotected information of the first and second manufacturer provided tothe first and second hardware security processors of the first andsecond client computing systems are used by the first and second clientcomputing systems to build a hardware-based root of trust to establishtrust between the first and second client computing systems; decrypting,by the first client computing system, using the first hardware securityprocessor, the encrypted license blob, and validating, by the firstclient computing system, using the first hardware security processor,the sub-license request, and on determination of allowance, creating, bythe first client computing system, using the first hardware securityprocessor, a sub-license to allow the second client computing system toplay the content; sending, by the first client computing system, usingthe first hardware security processor, the sub-license to the secondhardware security processor on the second client computing system,wherein the second hardware security processor encrypts the sub-licenseand provides the encrypted sub-license to the second sharing agent; andon sending the sub-license, providing, by the first client computingsystem, access to the content to the second client computing system. 2.The method of claim 1, wherein the encrypted license blob comprisessub-license information, the sub-license information comprising policiesdefining restrictions on sharing the content between the clientcomputing systems.
 3. The method of claim 1, wherein creating a securesession comprises using a trusted system attestation protocol withprivacy provision.
 4. The method claim 1, further comprising modifyingthe license blob, by the first client computing system, using the firsthardware security processor, to reflect sharing of the content;re-encrypting, by the first client computing system, using the firsthardware security processor, the license blob, and retuning, by thefirst client computing system, using the first hardware securityprocessor, the re-encrypted license blob to the first sharing agent,when a sub-license transfer is successful.
 5. The method of claim 1,wherein the second client computing system, using the second sharingagent, stores the encrypted sub-license in a memory of the second clientcomputing system.
 6. The method of claim 1, wherein on access of thecontent, the second client computing system plays the content accordingto the sub-license.
 7. A first client computing system equipped tosecurely share content with a second client computing system having asecond general purpose hardware processor, a second component, a secondsharing agent operated by the second general purpose hardware processor,and a second hardware security processor having second unique andprivacy protected information programmed of a second manufacturer of thesecond client computing system, the first client computing systemcomprising: a first general purpose hardware processor; a first hardwaresecurity processor that includes unique and privacy protectedinformation programmed by a first manufacturer of the first clientcomputing system; a first component to receive from a service providerserver content requested by a user and an encrypted license blobassociated with the content; a first sharing agent operated by the firstgeneral purpose hardware processor to connect with the second sharingagent operated by the second general purpose hardware processor on thesecond client computing system, and to cooperate with the second sharingagent to establish a secure session between the first hardware securityprocessor and the second hardware security processor of the secondclient computing system, the unique and privacy protected information ofthe first and second manufacturer provided to the first and secondhardware security processors of the first and second client computingsystems are used by the first and second client computing systems tobuild a hardware-based root of trust to establish trust between thefirst and second client computing systems; wherein the first hardwaresecurity processor is to decrypt the encrypted license blob, validate asub-license request, and on determination of allowance, create asub-license to allow the second client computing system to play thecontent, and to send the sub-license to a second hardware securityprocessor on the second client computing system, wherein the secondhardware security processor encrypts the sub-license and provide theencrypted sub-license to the second sharing agent; and wherein onsending of the sub-license, the first component is to provide access tothe content to the second client computing system.
 8. The first clientcomputing system of claim 7, wherein the encrypted license blobcomprises sub-license information, the sub-license informationcomprising policies defining restrictions on sharing the content betweenthe client computing systems.
 9. The first client computing system ofclaim 7, wherein the first and second sharing agents are to create thesecure session using a trusted system attestation protocol with privacyprovision.
 10. The first client computing system of claim 7, wherein thefirst hardware security processor is to modify the license blob toreflect sharing of the content, re-encrypt the license blob, and returnthe re-encrypted license blob to the first sharing agent, when asub-license transfer is successful.
 11. A non-transitorycomputer-readable storage medium comprising one or more instructionsthat when executed by a first general purpose hardware processor of afirst client computing system causes the first client computing systemto securely share content with a second client computing system, whereinto securely share content includes to: receive from a service providerserver content requested by a user and an encrypted license blobassociated with the content, the first client computing system, inaddition to the first general purpose hardware processor, having a firsthardware security processor that includes first unique and privacyprotected information of a first manufacturer of the first clientcomputing system; connect a first sharing agent operated by the firstgeneral purpose hardware processor on the first client computing systemwith a second sharing agent operated by a second general purposehardware processor on the second client computing system, the secondclient computing system, in addition to the second general purposehardware processor, further including a second hardware securityprocessor that includes second unique and privacy protected informationof a second manufacturer of the second client computing system; sendingthe encrypted license blob and a sub-license request from the firstsharing agent operated by the first general purpose hardware processorto the first hardware security processor on the first client computingsystem; creating, by the first sharing agent of the first clientcomputing system in cooperation with the second sharing agent of thesecond client computing system, a secure session between the firsthardware security processor of the first client computing system and thesecond hardware security processor of the second client computingsystem, wherein the unique and privacy protected information of thefirst and second manufacturers are used by the first and second clientcomputing systems to build a hardware-based root of trust to establishtrust between the first and second client computing systems; cause thedecrypting of the encrypted license blob by the first hardware securityprocessor, and validating the sub-license request by the first hardwaresecurity processor, and on determination of allowance, creating by thefirst hardware security processor a sub-license to allow the secondclient computing system to play the content, and cause the sending ofthe sub-license by the first hardware security processor to the secondhardware security processor on the second client computing system,wherein the second hardware security processor encrypts the sub-licenseand provides the encrypted sub-license to the second sharing agent; andon sending the sub-license, provide access to the content to the secondclient computing system.
 12. The computer-readable storage medium ofclaim 11, wherein the encrypted license blob comprises sub-licenseinformation, the sub-license information comprising policies definingrestrictions on sharing the content between the client computingsystems.